Corrugated plastic leaching chambers receive and disperse wastewater when buried within soil and other media. They have been described in various U.S. patents, including U.S. Pat. No. 4,759,661, No. 5,336,017, and No. 5,551,903, all of Nichols et al. Such chambers have been sold commercially as Infiltrator® chambers. The prior art Infiltrator chambers and competitor chambers generally have arch shape cross sections with opposing side perforated planar sidewalls running up to the chamber top from bases which have flanges to support the chamber on the media within which it is buried.
The present invention is concerned with chamber configuration and method of making the chamber, to achieve unusual improvement in nestability. In particular, there is a big increase in number of chambers which can be stacked in a given height space. The greater the density of nesting, the more economically can units be shipped and stored, since costs for such are primarily proportional to product volume, not weight.
In the arch shape cross section molded thermoplastic chambers known previously, ribs running lengthwise and cross wise within the arch interior have been used for providing strength. Those ribs and the corrugation shapes have limited what minimum nesting height can be achieved. Some special combinations of features have provided advances. For example, U.S. Pat. No. 5,551,903 of Nichols et al. at Table 4 describes the geometry and dimensions of chambers which have nest heights of 1.5 to 2.5 in. But there is a continuing desire for further improvement. For example, if a 0.5 in. reduction of a 1.5 in. nest height in. can be achieved, then 100 chambers can be stacked in the space previously occupied by 67 chambers. That could translate into as much as 33 percent reduction in shipping expense per chamber.
Recently, improved chambers have been introduced and sold commercially as Infiltrator® Quick4™ chambers. An exemplary chamber is illustrated by FIG. 1 herein. The chambers are further described in co-pending U.S. patent application Ser. No. 10/677,772 “Leaching Chamber with Inward Flaring Sidewall Perforations” of Swistak et al. and in the parent application herein. As reference to commercial products and the patent applications will show, the new chambers have various innovative features including a base flange with ribs and a lengthwise fin along the outer edge; and, sidewall slot perforations which are present to an elevation just above such kind of base flange.